TOKYO (Reuters) – The pace of approvals for nuclear reactor restarts in Japan, where most plants remain shut following the Fukushima disaster, is unlikely to pick up in the coming years, the new head of Japan’s nuclear regulator said in an interview on Tuesday.

The comments from Nuclear Regulation Authority (NRA) Chairman Toyoshi Fuketa suggest Japan may not make headway in meeting its electricity generation targets. By 2030, the country was expecting nuclear to power about one-fifth of its generation. However, utilities are having difficulty grappling with tougher rules on protecting reactors from natural disasters in the earthquake-prone country.

Following the Fukushima nuclear disaster in 2011, the world’s worst since Chernobyl in 1986, the NRA was set up in 2012 to draft new safety standards that have been described as among the world’s toughest.

Since then, 12 reactors at six nuclear plants have passed the safety requirements needed to restart, but only four reactors are currently operating. One more reactor that resumed operations after meeting the requirements has been shut down for scheduled maintenance.